While coronary heart disease (CHD) and ischemic stroke share some major risk factors, limited epidemiological data on dietary fats and vascular disease risk indicate that fatty acids have different associations with ischemic stroke than with CHD. The established associations between types of fat and CHD do not appear to apply to ischemic stroke. One explanatory hypothesis for the paradoxical observations is that arteriosclerosis in different types of cerebral arteries has different causal patterns. Particularly, atherosclerosis may only be involved in large artery infarction, and other risk factors such as blood pressure may play more important role in stroke development However, data on the associations of fatty acids and ischemic stroke and its subtypes including lacunar (small artery), atherosclerotic (large artery) and cardioembolic infarction are lacking. The general goal of this study is to examine the associations between serum fatty acids and risk of ischemic stroke and its subtypes among postmenopausal women. A prospective nested case-control study of 971 ischemic stroke cases and 971 matched controls in the Women's Health Initiative (WHI) Observational Study is proposed to achieve the objectives. Two major endeavors are planned for the proposed project: 1) assess serum fatty acids composition with previously collected and stored blood specimens;and 2) perform the statistical analyses, which undertake the specific aims and hypothesis. The proposed study will fill the gap in knowledge regarding associations of fatty acids and subtypes of ischemic stroke. Findings from this project will potentially help identify people at high risk of ischemic stroke as well as clarify possible differences between fatty acids and risk of ischemic stroke versus risk of CHD. The proposed study is to examine the associations between serum fatty acids and risk of ischemic stroke and its subtypes among postmenopausal women who are at increased risk of stroke. It is a timely and economical approach for investigating stroke risk in postmenopausal women. The data generated from this study should provide new information on the etiology of ischemic stroke and data for new explorations of dietary causes. PUBLIC HEALTH RELEVANCE: The proposed study is to examine the associations between serum fatty acids and risk of ischemic stroke and its subtypes among postmenopausal women who are at increased risk of stroke. It is a timely and economical approach for investigating stroke risk in postmenopausal women. The data generated from this study should provide new information on the etiology of ischemic stroke and data for new explorations of dietary causes.